Investigations, Claims, and Litigation (Narrative) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($) numberOfReinsurers	Sep. 30, 2020 USD ($) frigates
Loss Contingencies
Number of reinsurers/defendants | numberOfReinsurers	32
Bolivarian Republic of Venezuela
Loss Contingencies
Number of Foreign Built Frigates | frigates		2
Arbitral statement claim	$ 151	$ 151
Litigation counter claim [Member] | Bolivarian Republic of Venezuela
Loss Contingencies
Arbitral statement claim	$ 22	$ 22